| Author | Message | ||
     Duggram |
This time please try to comment on the question. I'm wandering if in the case of the 1125 if increasing bore to get ~70cc's is worthwhile. Any educated estimates out there? | ||
| Ducxl |
I'll try.On a similar engine i completed this year i addressed the pistons too. I decided on the 14:1CR pistons.I also had a choice between the stock 98mm bore,or overboring to the maximum of 100mm. The 100mm pistons provided a 4% increase in displacement. THe biggest bang,it was decided,came from the increased Compression Ratio. I went with the 98mm pistons and remachined the pistons to fit the combustion chamber. That ended up giving me closer to 13:1 Compression ratio.The engine was originally at 11.5:1 Adjusting the squish band(i did) to minimum can also increase CR a little  While VERY true that MY engine isn't an 1125r,the tech is exactly the same | ||
| Duggram |
Thanks for the replies. The smart answer to when will I do it is to wait to see what Dris comes up with. I am just wandering if it would be worth it to increase bore. Sounds like it might be for a track only bike. I realize that if I'm only going to be riding HWT and ULSB in club racing I could probably get away with it. Still probably is best to wait and see what Dris comes up with. | ||
| Slypiranna |
I'd wager Easyrider will have the largest bore possible!  For all we know, he might be playing with the stroke, rod ratio and any other possible gain within the Helicon! Gotta love him!  | ||
| Slypiranna |
FWIW, it would take just a hair over a 3mm overbore to get that 70cc's. Maybe there's room in there?  Anyone know available oversize slugs for this animal?  Manual should show safe overbore capacity as well...who's got that info now that Duggram sparked my interest? | ||
| Diablo1 |
You will however, be required to remap all areas of the fuel and timing maps. The timing will really need a lot more advance with an even larger bore than stock. It's already pushing over 60' lead in the rear cylinder stock! 63 degrees to be exact which is within a half of a degree of what this ecu's upper limit is. 60 degrees of advance???? Are you talking about full throttle or part throttle advance? I'd be shocked if it's more than 35 degrees. Something sounds screwy here.} | ||
| Slypiranna |
Diablo1, So be shocked. Stock max timing on rear cylinder is 63 degrees lead @ tps 9~15 / 6100~6900 rpm. But don't take my word for it, you can see it by scrolling down to the timing maps at the bottom of this screen shot... non-sponsor advertisement removed (Message edited by Blake on December 26, 2008) | ||
| Stormy |
That's part throttle. At 100% throttle max is 36deg @ 10700rpm | ||
| Stormy |
Those huge timing numbers at part throttle, higher rpm are often useful to prevent decell popping and delta tp popping conditions. | ||
| Blake |
Stormy is correct. The bike is not accelerating/pulling at 9-15% throttle and 6100-6900 rpm; that region of ignition advance mapping has no relation to the engine's high performance regions of operation. | ||
| Slypiranna |
I completely disagree with you on all accounts but no good can come of it for me to argue it. mm (Message edited by slypiranna on December 26, 2008) | ||
| Slypiranna |
Nope, I can't resist...I really did try tho while watching my guys thrash tonight over another BS subject relevant to this cause! While deep off throttle, in a way/lay over/racing/and getting SLOWLY back on the gun again, YOU WILL find the ecu on THIS loadpoint in question/NOT in decel BUT in ACCEL mode! Hello, read my loadpoint at said TPS/RPM? Geez...am I really the only one that is willing to post this? As you could also find in a street/transient situation, UNDER A LOAD POINT. PERIOD! Please don't argue otherwise as I'm NOT going to respond again to this sendoff. I remain, it counts but that was NOT and HAS NOTHING to do with what this thread was initiated upon, nor why I posted to it. It was simply to help and offer factual information, which has been deleted by Blake. Non of which was for advertisement purpose because if a paid advertiser here could post credible information relevant, I would have posted theirs instead. Not a BS post or three that could find reason to argue against. I'm pretty sure that the poster got that from his first attempt and that was why he posted another thread relevant to the first. Too much off topic, BS and without FACT is my take. Argue about it all you wish as I'm not checking in on this one again! I am learning better!  mm |
